1. Field of the Invention
This invention relates to an electric connector for electric equipment, particularly to an internal connector having a conducting shell mounted on the electric equipment, which is to mate with an external connector associated with an external cable.
2. Description of the Related Art
It has recently been required that a connector mounted on electric equipment, for lower cost and better portability be embedded in a chassis of the electric equipment, that is an internal connector. The cable connector is inserted into the mounted connector though a hole in the chassis, that is an external connector associated with an external cable is connected to the mounted connector. The internal connector has a conducting shell for an electrostatic shield against an electric field caused by high frequency signals from the electronic equipment. The shell encapsulates the entire surface of the connector except surfaces on which internal and external terminals are arranged. FIG. 1 shows a conventional connector 1 consisting of an external connector 11 associated with a cable 11a and an internal connector 12 having a shell 14 mounted on a chassis panel 16. The external connector 11 having an array of jacks on a front hollow is connected to external electric equipment (not shown) by the cable 11a. The internal connector 12 is composed of a connector body 13, an insulating mold 13b, an array of plugs 13a arranged on a front surface of the insulating mold 13b and the conducting shell 14 surrounding the array of plugs 13a. The shell 14 also has a pair of lugs 14b with a through hole 14c on each of them which fixes the shell to the front surface of the insulating mold 13b by a bolt. The connector body 13 is fixed on a circuit board 15 at an edge 15a where the circuit board 15 is fixed in perpendicular to the chassis panel 16 and in parallel to the plugs 13a. When the cable connector 11 is inserted in the internal connector 12 along the direction as indicated by an arrow G, each of the plugs 13a in the internal connector 12 mates with the corresponding one of the jacks in the cable connector to establish an electric connection between the external electric equipment and the electric equipment in interest. FIG. 2 illustrates how to ground the internal connector 12 to the chassis panel 16. In the first step, the internal connector 12 is fixed to the insulated front surface of the circuit board 15 by screwing a bolt 19a into a nut (not shown) at a through hole 15c on each side along the direction denoted by an arrow A such that each terminal of the plugs 13a' coincides with the corresponding terminal 15b of the circuit laid down on the front surface of the circuit board 15 for soldering. In the second step, the shell is fixed to the chassis panel 16 by a bolt 19b through a through hole 16b and 14c on each side such that the shell 14 is inserted into a window 16a of the chassis panel 16 along the direction denoted by an arrow B. Thus, since the conducting shell is internally connected with the ground terminal, the chassis panel 16 is grounded by contacting the lugs of the conducting shell 14 to the back surface of the chassis panel 16.
FIGS. 3A through 3D illustrate another conventional connector 2 consisting of an internal shelled connector 22 and an external cable connector 21. The external cable connector 21 is connected to external electric equipment (not shown) by a cable 21a. The internal shelled connector 22 is composed of a connector body 23 shown in FIG. 3B and a conducting shell 24 shown in FIG. 3D.
The connector body 23 is composed of an insulating mold 232, an array of plugs 231, and an external plug terminal 231b. The array of plugs 231 is arranged such that each of the plug terminals 231a is to mate with the corresponding jack terminal in an array of jacks (not shown) of the external cable connector 21, which is extended to the external plug terminal 231b as shown in FIG. 3C, which is sticking out of the insulating mold 232 arranged perpendicular to the plug terminal 231a. The insulating mold 232 is formed by an insert mold method such that the array of plugs 231 is surrounded by insulating walls 232a and 232c. Further, the insulating mold 232 has a rectangular boss 232b on each side of both walls 232a. As shown in FIG. 3D, the shell 24 is formed by holding a single sheet of patterned aluminum such that all of the outer surfaces of the connector body 23 are encapsulated except the front opening in which the cable connector 21 is to be inserted, a part of the bottom surface on which an array of the external plug terminals 231b is arranged, and a rectangular opening 24a on each of both side walls to which the rectangular boss 232b is engaged. The shell 24 has a pair of outwardly curved legs 24b on both sides extending to the same direction as that of the external plug terminals 231b by which the internal shelled connector 22 is temporarily fixed to the circuit board as described in detail later. Thus, the internal shelled connector 22 will be built as shown in FIG. 3A by inserting the connector body 23 into the shell 24 such that the rectangular boss 232b is engaged with the rectangular opening 24a on each of both side walls 232a.
FIG. 4A and 4B show how to mount the internal shelled connector 22 on the electric equipment and how to ground the chassis panel 26 to the internal shelled connector 22, respectively. First, the internal shelled connector 22 is mounted near the edge 25a of the circuit board 25 such that an array of the external plug terminals 231b and a pair of outwardly curved legs 24b are inserted into the through holes 25b and 25c to be fixed, respectively. Next, the circuit board 25 is fixed to the chassis panel 26 by screwing a bolt 27 into a through hole 25e on the circuit board 25 and an adjustable channel 26c on a plate 26b extended perpendicularly to the chassis panel 26 with a nut 28 such that the front surface of the shell 24 is aligned to the back surface of the chassis panel 26 on a periphery of the opening 26a to expose the array of plugs 231b therein by sliding the bolt in the adjustable channel 26c along the direction of a bilateral arrow D.
The through holes 25b and 25c are connected to the corresponding signal terminals (not shown) and a ground terminal 25d on the back surface, respectively. Each of the external plug terminals 231b inserted in the through holes 25b is soldered to the corresponding signal terminal, and also each of the penetrated outwardly curved legs 24b is bent and fixed to the ground terminal 25d on the back surface of the circuit board 25. Thus, the ground potential is ensured for the shell 24 by soldering the legs 24b to the ground terminals 25d. However, since in the shelled connector 12 as shown in FIG. 2, grounding the shell 14 is established only by contacting the lug 14b to the chassis panel 16 with screwing a bolt 19b and a nut (not shown), an oxidized layer or any insulating foreign material on the contact surface may easily cause instability in an electric contact between the lug 14b and the chassis panel 16 and even disconnection of the shell 14 to the ground potential. Since in the shelled connector 22 as shown in FIG. 4A, grounding the shell 14 is established by soldering the legs 24b to the ground terminals 25d, it is needed to form the ground terminals 25d on the back surface of the circuit board 25 solely for this purpose, and also a shell material is limited to metals that can be soldered.